<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .wrapper{
            min-height: 100vh;
            display: flex;
            flex-direction: column;
        }

        .content{
            flex:1;
            margin-bottom: 20px;
            background: red;
        }

        .footer{
            background: pink;
            height: 40px;
        }
    </style>
</head>
<body>
   <div class="wrapper">
       <div class="content">
           
       </div>
       <div class="footer"></div>
   </div>
</body>
</html>